Processing system

ABSTRACT

A processing system has an upper electrode with gas discharge holes of a shape corresponding to the external we of insulating members. The insulating members are formed of a poly(ether etherketone) resin, a polyimide resin, a poly (ether imide) resin or the like. Each insulating member has a step at its outer surface and an internal longitudinal through hole tapered to expand toward the processing chamber. The insulating members are pressed in the gas discharge holes to bring the steps into contact with shoulders formed in the sidewalls of the gas discharge holes. A part of each insulating member, as fitted in the gas discharge hole, projects from a surface of the upper electrode that faces a susceptor.

This application is a division of U.S. patent application Ser. No.10/278,863, filed Oct. 24, 2002, which is a reissue of U.S. Pat. No.6,334,983, which resulted from U.S. patent application Ser. No.09/402,393, filed Oct. 5, 1999, which was a 35 U.S.C. 371 National stagefiling of PCT/JP/98/0160 PCT/JP98/01610, filed Apr. 8, 1998. Thisapplication is one of three divisions of U.S. patent application Ser.No. 10/278,863, the other two divisions being U.S. patent applicationSer. No. 10/463,439, filed Jun. 18, 2003, and U.S. patent applicationSer. No. 11/055,788, filed Feb. 11, 2005.

TECHNICAL FIELD

The present invention relates to a processing system, such as an etchingsystem.

BACKGROUND ART

A prior art etching system is provided with an upper electrode and asusceptor serving as a lower electrode disposed opposite to each otherin a processing chamber formed in an airtight processing vessel. Whensubjecting a workpiece to a predetermined etching process by thisetching system, the workpiece is mounted on the susceptor, apredetermined process gas is supplied into the processing chamber andthe workpiece is etched for the predetermined etching process by aplasma produced in the processing chamber by applying a predeterminedradio frequency power across the upper electrode and the susceptor. Theprocess gas is supplied through a gas supply pipe connected to gassources, for example, into a space defined between the upper electrodeand an upper electrode holding member holding the upper electrode, andthen the process gas is discharged through a plurality of gas dischargeholes formed in the upper electrode into the processing chamber.

Since a surface of the upper electrode facing the susceptor is exposedto the plasma, it is possible that an electric field is concentrated onthe gas discharge holes, more specifically on the edges of the gasdischarge holes on the side of the processing chamber, whereby the edgesof the gas discharge holes are etched and particles are produced. If theparticles adhere to the workpiece, the yield of the products of theetching system is reduced. A technique disclosed in, for example, JP-ANo. 61-67922 inserts insulating members each provided with a throughhole and formed of a ceramic material, such as alumina, or afluorocarbon resin, such as Teflon in the gas discharge holes to preventthe concentration of an electric field on the gas discharge holes. Thegas discharge holes are tapered toward the processing chamber, and theinsulating members substantially tapered so as to conform with thetapered gas discharge holes are inserted downward from the upper end ofthe gas discharge holes in the gas discharge holes. The insulatingmembers are fitted in the gas discharge holes so that the lower endsurfaces thereof on the side of the processing chamber are flush withthe surface of the upper electrode facing the susceptor. Thus, theinsulating members are not caused to fall off the upper electrode towardthe lower electrode by the pressure of the process gas, and prevent theconcentration of an electric field on the gas discharge holes.

Since the insulating members are inserted in the gas discharge holesfrom the upper side of the upper electrode, the upper electrode needs tobe removed from the processing vessel every time the insulating membersare changed and hence the work for changing the insulating member takesmuch time, the operating time of the etching system is reducedaccordingly, reducing the throughput of the etching system. Since theprocessing chamber is heated at a high temperature during the processingoperation of the etching system, thermal stress is induced in the upperelectrode. Consequently, the gas discharge holes and the insulatingmembers are strained and, sometimes, the lower end surfaces of theinsulating members on the side of the processing chamber are dislocatedfrom a plane including the lower surface of the upper electrode facingthe lower electrode.

Sometimes, the edges of the through holes of the insulating member onthe side of the processing chamber are etched by the plasma produced inthe processing chamber and particles are produced. Since the insulatingmembers are made of alumina or a fluorocarbon resin, it is possible thatparticles of aluminum or the fluorocarbon resin are produced, and theparticles adhere to the workpiece and exert adverse effects, such as thereduction of insulating strength, on the workpiece.

In a processing system provided with an upper electrode comprising anupper electrode member and a cooling plate placed on the upper electrodemember, both the upper electrode member and the cooling plate areprovided with a plurality of gas discharge holes. In this processingsystem, a plasma produced in a processing chamber flows through the gasdischarge holes formed in the upper electrode member and the gasdischarge holes of the cooling plate are damaged by the plasma.

DISCLOSURE OF THE INVENTION

The present invention has been made in view of the foregoing problems inthe prior art processing systems and it is therefore an object of thepresent invention to provide a novel, improved processing systemprovided with insulating members capable of being easily attached andchanged and of being easily and uniformly positioned.

The present invention is applied to a processing system comprising aprocessing vessel defining an airtight processing chamber, upper andlower electrodes disposed opposite to each other in the processingchamber, and constructed to supply a predetermined process gas through aplurality of gas discharge holes formed in the upper electrode into theprocessing chamber. According to a first aspect of the presentinvention, insulating members each provided with a through holepermitting a process gas to pass through are fitted in the gas dischargeholes, respectively, from the side of the processing chamber. Since theinsulating members are inserted and fitted in the gas discharge holesthrough the outlet ends (ends on the side of the processing chamber) ofthe gas discharge holes, the insulating members can easily be attachedto the upper electrode and easily be changed.

According to a second aspect of the present invention, the insulatingmembers are fitted in the gas discharge holes of the upper electrode soas to project from the lower surface of the upper electrode facing thelower electrode into the processing chamber. Since lower end parts ofthe insulating members project from the lower surface of the upperelectrode facing the lower electrode, the edges of ends of the gasdischarge holes on the side of the processing chamber are not exposed tothe processing chamber. Consequently, the edges not exposed to theprocessing chamber are not etched by a plasma produced in the processingchamber for a processing operation.

According to a third aspect of the present invention, each of theinsulating members is provided with a flange capable of covering the rimof an end of the gas discharge hole on the side of the processingchamber. When the insulating members are fitted in the gas dischargeholes, respectively, the flanges cover the rims of the ends of the gasdischarge holes on the side of the processing chamber. Therefore, theedges of the ends of the gas discharge holes on the side of theprocessing chamber are not exposed to a plasma produced in theprocessing chamber and will not be etched. Thus, the life of the upperelectrode provided with the gas discharge holes can greatly be extended.

According to a fourth aspect of the present invention, each of the gasdischarge holes is provided with a shoulder, each of the insulatingmembers is provided with a step, and the insulating members are fittedin the gas discharge holes so that the insulating members are positionedin place in the gas discharge holes with the steps thereof resting onthe shoulders of the corresponding gas discharge holes. Since theinsulating members are pressed into the gas discharge holes so that thesteps are pressed against the shoulders of the gas discharge holes, theinsulating members can correctly be positioned. Consequently, all theinsulating members can be positioned at desired positions in the gasdischarge holes. Since the steps of the insulating members are in closecontact with the shoulders of the gas discharge holes, the plasma isunable to leak into a gas supply passage connected to the gas dischargeholes.

According to a fifth aspect of the present invention, at least a part ofthe sidewall of each of the gas discharge holes between the open endthereof on the side of the processing chamber and the shoulder thereofis finished by a plasma-proofing process, such as an anodic oxidationprocess if the upper electrode is formed of aluminum. Therefore, thesidewalls of the gas discharge holes are not etched even if the plasmainfiltrates into gaps between the sidewalls of the gas discharge holesand the insulating members. Since a part of the sidewall of each gasdischarge hole between the shoulder and the open end opening into thegas supply passage is not finished by the plasma-proofing process, theouter surfaces of the insulating members and the sidewalls of thecorresponding gas discharge holes are in airtight contact with eachother. Therefore, the insulating members will not come off the gasdischarge holes even if the pressure of the gas acts on the insulatingmembers.

According to a sixth aspect of the present invention, the length of theinsulating members is shorter than that of the gas discharge holes. Wheneach insulating member is fitted in the gas discharge hole, a space isformed between the insulating member fitted in the gas discharge holeand the gas supply passage. Therefore, an optimum conductance can besecured and the process gas can be discharged in a desired mode throughthe through holes of the insulating members into the processing chamber.

According to a seventh aspect of the present invention, at least a partof the through hole of each insulating member is substantially taperedso as to expand toward the processing chamber. Since any edge is notformed in the open end of through hole on the side of the processingchamber, the insulating members have improvised plasma resistance, andinsulating member changing period can greatly be extended. Since theparts of the through holes of the insulating members are tapered so asto expand toward the processing chamber, the process gas can uniformlybe distributed over a workpiece placed in the processing chamber.

According to an eighth aspect of the present invention, the insulatingmembers are formed of a resin, such as a poly (ether ether ketone) resinof the formula (1), such as PEEK PK-450 commercially available fromNippon Poripenko K.K. or PEEK PK-450G commercially available from ThePolymer Corp., a polyimide resin of the formula (2), such a VESPEL SP-1commercially available from DuPont, or a poly(ether imide) resin of theformula (3), such as ULTEM UL-1000 (natural grade) commerciallyavailable from Nippon Poripenko K.K. or The polymer Corp.

The insulating members has an improved plasma resistance, insulatingmember changing period can greatly be extended, and influence on theworkpiece can be limited to the least extent even if the insulatingmembers are etched by the plasma.

According to a ninth aspect of the present invention, a processingsystem comprises: a processing vessel having an airtight processingchamber, an upper electrode disposed in an upper region of theprocessing chamber, and a lower electrode disposed below and opposite tothe upper electrode in the processing chamber; wherein the upperelectrode has an upper electrode member and a cooling plate disposed onthe upper electrode member, the upper electrode member and the coolingplate are provided with a plurality of gas discharge holes through whicha predetermined process gas is supplied into the processing chamber, andinsulating members each provided with a through hole permitting theprocess gas to flow through are fitted in the gas discharge holes so asto cover the sidewalls of the gas discharge holes. Thus, it is possibleto prevent the etching of the sidewalls of the gas discharge holes ofthe cooling plate by a plasma produced in the processing chamber.

According to a tenth aspect of the present invention, at least an endpart of the through hole of each insulating member on the side of theprocessing chamber is substantially tapered so as to expand toward theprocessing chamber. The insulating members provided with the throughholes having the substantially tapered parts, respectively, are noteasily etched, and insulating member changing period can be extended.

According to an eleventh aspect of the present invention, each of thegas discharge holes of the cooling plate is provided with a shoulder,each of the insulating members is provided with a step, and theinsulating members are fitted in the gas discharge holes so that theinsulating members are positioned in place in the gas discharge holeswith the steps therefor resting on the shoulders of the correspondinggas discharge holes. Since the insulating members are pressed into thegas discharge holes so that the steps are pressed against the shouldersof the gas discharge holes, the insulating members can correctly bepositioned. Consequently, all the insulating members can be positionedat a desired position in the gas discharge holes of the cooling plate.

As mentioned above, according to the present invention, the insulatingmembers are fitted in the gas discharge holes, respectively, of theupper electrode from the side of the outlet ends of the gas dischargeholes (from the side of the processing chamber). Therefore, theinsulating members can easily be attached to and removed from the upperelectrode. Since the insulating members are positioned in place in thegas discharge holes with the steps thereof resting on the shoulders ofthe corresponding gas discharge holes, the insulating members canuniformly be disposed in the gas discharge holes. Since any edge is notformed in a part of each insulating member exposed to the atmosphere ofthe processing chamber and a part of the through holes of eachinsulating member is substantially tapered so as to expand toward theprocessing chamber, the insulating members are not easily etched andinsulating member changing period can be extended. The insulatingmembers formed of a predetermined resin have improved plasma resistanceand extend insulating member changing period. Since a part of each ofthe sidewalls of the gas discharge holes between the open end thereof onthe side of the processing chamber and the shoulder thereof is finishedby a plasma-proofing process, and edges of the open ends of the gasdischarge holes on the side of the processing chamber are covered withthe insulating members, the life of the upper electrode can be extended.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of an etching system in a firstembodiment according to the present invention;

FIG. 2 is a schematic enlarged sectional view of a part of the etchingsystem of FIG. 1 around a gas discharge hole;

FIG. 3 is a schematic perspective view of an insulating member employedin the etching system of FIG. 1;

FIG. 4 is a schematic sectional view of am insulating member in amodification of the insulating member shown in FIG. 3;

FIG. 5 is a schematic sectional view of an insulating member in anothermodification of the insulating member shown in FIG. 3;

FIG. 6 is a schematic sectional view of a part of an etching system inanother embodiment according to the present invention around gasdischarge holes; and

FIG. 7 is an enlarged sectional view of a part of FIG. 6 around a gasdischarge hole.

BEST MODE FOR CARRYING OUT THE INVENTION

Processing systems in preferred embodiments according to the presentinvention as applied to etching systems will be described with referenceto the accompanying drawings, in which parts of substantially the samefunctions and the same formation will be designated by the samereference characters and the duplicate description thereof will beomitted.

FIG. 1 is a schematic sectional view of an etching system 100 in a firstembodiment according to the present invention. The etching system 100has a substantially cylindrical processing vessel 104 of, for example,aluminum having surfaces finished by an anodic oxidation process,defining a processing chamber 102 and capable of being sealed in anairtight fashion. The processing vessel 104 is connected to a ground bya grounding line 106. An insulating support plate 108 of, for example, aceramic material is disposed in the bottom of the processing chamber102. A substantially cylindrical susceptor 110 serving as a support forsupporting a workpiece, such as a 12 in. diameter semiconductor wafer W(hereinafter referred to simply as “wafer”) W, and as a lower electrodeis disposed on the insulating support plate 108.

The susceptor 110 is supported on a lifting shaft 112 extending throughthe insulating support plate 108 and the bottom wall of the processingvessel 104. The lifting shaft 112 is connected to a driving mechanism,not shown, disposed outside the processing vessel 104. The drivingmechanism moves the susceptor 110 in vertical directions as indicated bythe arrows in FIG. 1. An elastic airtight sealing member, such as abellows 114, is extended between the susceptor 110 and the insulatingsupport plate 108 so as to surround the lifting shaft 112.

The susceptor 110 is formed of, aluminum and has surfaces finished by ananodic oxidation process. A coolant circulating passage 116 is formed inthe susceptor 110. The coolant circulating passage 116 is connected to acoolant source, not shown, disposed outside the processing vessel 104 bya coolant supply pipe 116a and a coolant discharge pipe 116b. A coolant,such as ethylene glycol, is circulated through the coolant circulatingpassage and the coolant source. The susceptor 110 is internally providedwith a heating device, not shown, such as a ceramic heater, and atemperature sensor, not shown. The heating device, he temperature sensorand the coolant circulating passage 116 cooperate to maintain the waferW automatically at a desired temperature.

An electrostatic chuck 118 for attracting and holding the wafer W ismounted on a mounting surface of the susceptor 110. The diameter of theelectrostatic chuck 118 is substantially equal to that of the wafer W.The electrostatic chuck 118 is formed by sandwiching an electricallyconductive thin film 118a such as a tungsten thin film, betweeninsulating members 118b of, for example, a ceramic material. The thinfilm 118a is connected to a variable dc power supply 120. When a high dcvoltage in the range of, for example, 1.0 to 2.5 kV is applied to thethin film 118a by the variable dc power supply 120, Coulomb's force andJohonson-Rahbeck force are generated in the insulating members 118b andthe electrostatic chuck 118 attracts the wafer W mounted thereon to itssupport surface and holds the wafer W in place. A plurality of heattransfer gas jetting holes 122 opens in the support surface of theelectrostatic chuck 118. The heat transfer gas jetting holes 122 areconnected to a heat transfer gas source, not shown, by a heat transfergas supply pipe 124. When processing the wafer W, a heat transfer gas,such as He gas, is jetted through the heat transfer gas jetting holes122 into minute spaces between the back surface of the wafer W mountedon the electrostatic chuck 118 and the support surface to transfer heatgenerated in the wafer W efficiently to the susceptor 110.

The electrostatic chuck 118 is provided with a through hole, not shown,and a lifting pin is inserted in the through hole so as to be verticallymovable. The lifting pin can be projected form and retracted beneath thesupport surface of the electrostatic chuck 118. The lifting pin operatesto transfer the wafer W in a desired mode between a carrying arm, notshown, and the support surface.

A substantially annular focus ring 126 of, for example, quartz isdisposed in a peripheral part of the mounting surface of the susceptor110 so as to surround the electrostatic chuck 118. The focus ring 126enables a plasma to fall effectively on the wafer W for the uniformprocessing of the wafer W.

An upper electrode 128 is disposed opposite to the mounting surface ofthe susceptor 110. The upper electrode 128 is made of an electricallyconductive material, such as aluminum, in a shape substantiallyresembling a disk, and has surfaces finished by an anodic oxidationprocess. The upper electrode 128 is attached closely to an upperelectrode support member 130 of an electrically conductive material. Theupper electrode 128 and the upper electrode support member 130 are heldby a substantially annular insulating ring 132 attached to the top wall104a of the processing vessel 104.

A recess is formed in a surface of the upper electrode support member130 facing the upper electrode 128 to define a space 134 between theupper electrode support member 130 and the upper electrode 128 asattached to the upper electrode support member 130. A gas supply pipe136 is connected to a part of the upper electrode support member 130corresponding to a central region of the space 134. The gas supply pipeis connected through a valve 138 and a flow controller (MFC) 140 to agas source 142.

The upper electrode 128 is provided with a plurality of gas dischargeholes 128a connecting the space 134 to the processing chamber 102.Insulating members 144 relevant to this embodiment are fitted in the gasdischarge holes 128a, respectively.

The insulating members 144 relevant to this embodiment will bedescribed. The insulting members are formed of a plasma-resistant resin,such as poly(ether ether ketone) resin of the formula (1), a polyimideresin of the formula (2) or a poly(ether imide) resin of the formula(3).

The plasma resistance of the insulating members 144 will be describedbelow. The poly(ether ether ketone) resin of the formula (1), thepolyimide resin of the formula (2), the poly(ether imide) resin of theformula (3), a polytetrafluoroethylene resin (fluorocarbon resin) of theformula (4) and a polychlorotrifluoroethylene resin (fluorocarbon resin)of the formula (5) were subjected to etching under the following etchingconditions and the etch rates of those resins were measured.

-   -   (1) Process gases: CHF₃:CF₄:Ar=20:40:60 (sccm)    -   (2) Pressure in the processing chamber: 300 mrTorr    -   (3) Plasma producing radio frequency power: 1.5 kW

The etch rate ratios between the measured etch rates of the resins werecalculated.

Calculated each rate ratios

-   -   (1) Polytetrafluoroethylene/Poly(ether ether ketone)=17.5    -   (2) Polytetrafluoroethylene/polyimide=16.5    -   (3) Polytetrafluoroethylene/Poly(ether imide)=14.1    -   (4) Polychlorotrifluoroethylene/Poly(ether ether ketone)=52.4    -   (5) Polychlorotrifluoroethylene/Polyimide=49.4    -   (6) Polychlorotrifluoroethylene/Poly(ether imide)=42.2

It is known from those etch rates that the poly(ether ether ketone)resin, the polyimide resin and the poly (ether imide) resin for formingthe insulating members 144, as compared with the polytetrafluoroethyleneresin and the polychlorotrifluoroethylene resin, which are fluorocarbonresins, are very highly resistant to etching. It is considered thatfluorocarbon resins including the polytetrafluoroethylene resin and thepolychlorotrifluoroethylene resin are easily etched because fluorocarbonresins are highly reactive with and easily dissociated by process gasescontaining fluorine and generally used for etching processes, such asCF₄, CHF₃ and CH₂F₂.

The shape of the insulating members 144, and the shape of the gasdischarge holes 128a in which the insulating members 144 are fitted willbe descried with reference to FIGS. 2 and 3.

The insulating member 144 has a substantially T-shaped longitudinalsection as shown in FIG. 2, and is provided with a step 144a as shown inFIGS. 2 and 3. The insulating member 144 has an expanded part 144b of arelatively great diameter on one die of the step 144a, and a reducedpart 144c of a relatively small diameter on the other side of the step144a. The insulating member 144 has a length shorter than that of thegas discharge hole 128a.

The insulating member 144 is provided with a longitudinal through hole144d. An end part of the through hole 144d opening in the expanded part144b is substantially tapered so as to expand toward its open end.Therefore, the process gas can be discharged in a desired mode throughthe through hole 144d, the sidewall of the tapered part of the throughhole 144d is hardly etched and hence insulating member changing periodat which the insulating members 144 are changed can be extended. Edgesof the insulating member 144 which will be exposed to the atmosphere ofthe processing chamber 102 when the insulating member 144 is fitted inthe gas discharge hole 128a are rounded, which further enhances the etchresistance of the insulating member 144 and further extends insulatingmember changing period.

As shown in FIG. 2, the gas discharge hole 128a has a shape fitting theinsulating member 144. A shoulder 128b is formed in the gas dischargehole 128a at a position corresponding to the step 144a of the insulatingmember 144. A part of the gas discharge hole 128a on the side of theprocessing chamber 102 with respect to the shoulder 128b has a diametercorresponding to that of the expanded part 144b of the insulating member144, and another part of the gas discharge hole 128a on the side of thespace 134 with respect to the shoulder 128b has a diameter correspondingto that of the reduced part 144c of the insulating member 144. A part ofthe sidewall of the gas discharge hole 128a between the open end openinginto the processing chamber 102 and the shoulder 128b is finished by aplasma-proofing process, such as an anodic oxidation process by whichthe surfaces of the upper electrode 128 are finished. Therefore, thesidewalls of the gas discharge holes are not etched even if the plasmainfiltrates into gaps between the sidewalls of the gas discharge holes128a and the insulating members 144.

A method of fitting the insulating member 144 in each of the pluralityof gas discharge holes 128a will be described below. The insulatingmember 144 is inserted in the gas discharge hole 128a from the side ofthe outlet end of the gas discharge hole 128a, i.e., from the side ofthe processing chamber 102. The insulating member 144 is pressed so thatthe step 144a of the insulating member 144 comes into contact with theshoulder 128b of the gas discharge hole 128a. Thus, the insulatingmembers 144 can easily be positioned and can uniformly be arranged inthe gas discharge holes 128a.

A part of the gas discharge hole 128a between the shoulder 128b and anopen end opening into the space 134 is not finished by a plasma-proofingprocess, because fine irregularities are formed in the sidewall of thegas discharge hole 128a if the sidewall of the gas discharge hole 128ais finished by a plasma-proofing process, such as anodic oxidationprocess, and the closeness of contact between the sidewall of the gasdischarge hole 128a and the outer surface of the reduced part 144c ofthe insulating member 144 is deteriorated. Thus, the outer surface ofthe reduced part 144c of the insulating member 144 is in close contactwith the sidewall of the gas discharge hole 128a. Consequently, theplasma is unable to infiltrate into gaps between the sidewalls of thegas discharge holes 128a and the insulating members 144, and theinsulating members 144 will not be caused to come off the gas dischargeholes 128a by the pressure of the process gas.

When the insulating member 144 is fitted in the gas discharge hole 128a,a part of the insulating member 144 projects from a surface of the upperelectrode 128 facing the susceptor 110 as shown in FIG. 2. Therefore,the edge of the open end of the gas discharge hole 128a on the side ofthe processing chamber 102 is not exposed to the plasma produced in theprocessing chamber 102 and is protected from etching, so that upperelectrode changing period at which the upper electrode 128 is changedcan be extended. When the insulating member 144 is fitted in the gasdischarge hole 128a, a space is formed between the insulating member 144and the space 134 extending over the upper electrode 128.

An insulating member 200 shown in FIG. 4 may be fitted instead of theforegoing insulating member 144 in the gas discharge hole 128a.

The insulating member 200 is formed by additionally providing theinsulating member 144 with a flange 200a around the part of theinsulating member 144 that projects from the upper electrode 128 intothe processing chamber 102 when the insulating member 144 is fitted inthe gas discharge hole 128a. The insulating member 200 is substantiallyidentical in shape with the insulating member 144, except that theinsulting member 200 is provided with the flange 200a. When theinsulating member 200 is fitted in the gas discharge hole 128a, theflange 200a of the insulating member 200 covers closely the edge of anopen end of the gas discharge hole 128a on the side of the processingchamber 102 and the rim of the open end of the same. Consequently, theedge of the open end of the gas discharge hole 128a on the side of theprocessing chamber 102 is not exposed to the plasma and is not etched,which extends the life of the upper electrode 128 provided with the gasdischarge holes 128a greatly.

An insulating member 210 shown in FIG. 5 may be fitted instead of theinsulating members 144 and 200 in the gas discharge hole 128a.

The insulating member 210 has a flange 210a corresponding to the flange200a of the insulating member 200 and does not have any partcorresponding to the step 144a of the insulating member 200. Theinsulating member 200 is positioned by either bringing the step 144ainto contact with the shoulder 128b or bringing the flange 200a intocontact with the surface of the upper electrode 128. The insulatingmember 210 is positioned only by bringing the flange 210a into contactwith the surface of the upper electrode 128.

When the insulating member 210 is fitted in the gas discharge hole 128a,the flange 210a of the insulating member 210 covers closely the edge ofan open end of the gas discharge hole 128a on the side of the processingchamber 102 and the rim of the open end of the same. Consequently, theedge of the open end of the gas discharge hole 128a on the side of theprocessing chamber 102 is not exposed to the plasma and is not etched,which extends the life of the upper electrode 128 provided with the gasdischarge holes 128a greatly.

A method of supplying a process gas into the processing chamber 102 willbe described below.

A predetermined process gas, such as a mixed gas of CF₄ gas and O₂ gaswhen processing a silicon dioxide film, is supplied from the gas source142 (FIG. 1) through the gas supply pipe 136 provided with the flowcontroller (MFC) 140 and the valve 138 into the space 134. The processgas fills up the space 134 and the spaces in the gas discharge holes128a. Consequently, an optimum conductance can be secured. The processgas flows from the spaces in the gas discharge holes 128a through thethrough holes 144d into the processing chamber and is distributeduniformly in a desired mode over the wafer W mounted on the susceptor110.

Referring again to FIG. 1, an exhaust pipe 146 has one end connected toa lower part of the side wall of the processing vessel 104, and theother end connected to a vacuum pump (P) 148, such as a turbo-molecularpump. The vacuum pump 148 operates to evacuate the processing chamber102 to a predetermined reduced pressure, such as a vacuum in the rangeof several millitorrs to several hundreds millitorrs and to maintain thepredetermined vacuum.

A radio frequency power supply system included in the etching system 100will be described below. A first radio frequency generator 152 isconnected through a first matching circuit 150 to the upper electrode128. A second radio frequency generator 156 is connected through asecond matching circuit 154 to the susceptor 110. In operation, thefirst radio frequency generator 150 supplies plasma producing radiofrequency power of, for example, 13.56 MHz to the upper electrode 128.Then, the process gas supplied into the processing chamber 102 isdissociated and a plasma is produced. At the same time, the second radiofrequency generator 156 supplies a predetermined bias radio frequencypower of, for example, 380 kHz to the susceptor 110 to attract theplasma effectively to the surface to be processed of the wafer W.

The present invention is not limited to the etching system 100 and maybe embodied, for example, in an etching system provided with an upperelectrode to which radio frequency power is supplied, and a susceptorand a processing vessel connected to a ground or an etching systemprovided with a susceptor to which radio frequency power is supplied,and an upper electrode and a processing vessel connected to a ground.

The insulating members 144 of the etching system in this embodiment thusconstructed are fitted in the gas discharge holes 128a through theoutlet ends thereof on the side of the processing chamber 102.Therefore, the insulating members 144 can easily be changed. Since theinsulating members 144 are positioned by bringing the steps 144a thereofinto contact with the shoulders 128b of the gas discharge holes 128a,the insulating members 144 can easily be positioned and can uniformly bearranged. Since any edge is not formed in a part of each insulatingmember 144 exposed to the atmosphere of the processing chamber 102 and apart of the through hole 144d of each insulating member 144 issubstantially tapered, the insulating members have improved etchresistance and insulating member changing period can be extended. Theinsulating members formed of the foregoing resin have improved plasmaresistance and extend insulating member changing period. Since a part ofthe sidewall of each gas discharge hole 128a between the open endthereof on the side of the processing chamber 102 and the shoulder 128bthereof is finished by a plasma-proofing process, and edges of the openends of the gas discharge holes 128a on the side of the processingchamber 102 are covered with the insulating members 144, upper electrodechanging period at which the upper electrode 128 is changed can beextended.

An upper electrode 228 of a construction different from that of theupper electrode 128 of the etching system 100 shown in FIG. 1 will bedescribed with reference to FIGS. 6 and 7.

The upper electrode 228 is applied to an etching system having a plasmaprocessing ability higher than that of the etching system 100 shown inFIG. 1. In the following description, components of the upper electrode228 substantially the same in function and construction as those of theupper electrode 128 will be designated by the same reference charactersand the description thereof will be omitted to avoid duplication.

The upper electrode 228 comprises a silicon electrode (upper electrodemember) 301 disposed opposite to a mounting surface of a susceptor 110,and a cooling plate 302 of an aluminum alloy bonded to the upper surfaceof the silicon electrode 301.

The silicon electrode 301 is provided with a plurality gas dischargeholes 301a. The cooling plate 302 is provided with a plurality of gasdischarge holes 302a of a diameter greater than that of the gasdischarge holes 301a. The gas discharge holes 301a and the gas dischargeholes 302 are coaxial, respectively. A space 134 communicates with aprocessing chamber 102 by means of the gas discharge holes 301a and302a.

Each of the gas discharge holes 302 has a cylindrical, reduced lowerpart, and a cylindrical expanded upper part. The reduced lower part andthe expanded upper part are demarcated by a shoulder 302b.

Insulating members 244 of the same material as the insulating member 144are fitted in the gas discharge hole 302a, respectively, so as to bereplaceable when damaged.

Referring to FIG. 7, the insulating member 244 has a cylindrical,reduced lower part 244a, and a cylindrical expanded upper part 244b. Thereduced lower part 244a and the expanded upper part 244b are demarcatedby a step 244f. The cylindrical, reduced lower part 244a is fitted inthe cylindrical, reduced lower part of the gas discharge hole 302a, andthe cylindrical expanded upper part 244b is fitted in the cylindrical,expanded upper part of the gas discharge hole 302a.

The length of the insulating member 244 is approximately equal to thethickness of the cooling plate 302. The lower end surface of theinsulating member 244 is substantially in contact with the upper surfaceof the silicon electrode 301. The length of the insulating member 244may be smaller than the thickness of the cooling plate 302, providedthat the lower end surface of the insulting member 244 is substantiallyin con tact with the upper surface of the silicon electrode 301. Thecylindrical, reduced lower part 244a is provided with a small hole 244cof a diameter substantially equal to that of the gas discharge hole301a, and the cylindrical, expanded part 244b is provided with a largehole 244d of a diameter greater than that of the small hole 244c.

The small hole 244c has a tapered lower end part 244e expanding towardthe lower open end thereof on the side of the gas discharge hole 301a.The tapered end part 244e does not have any edges and has a smoothsurface.

The step 244f can be brought into contact with the shoulder 302b toposition the insulating member 244 longitudinally on the cooling plate302.

A part of the sidewall of the gas discharge hole 302a between theshoulder 302b and the upper open end on the side of the space 134 is notfinished by a plasma-proofing process, because fine irregularities areformed in the sidewall of the gas discharge hole 302a if the samesidewall is finished by a plasma-proofing process, such as anodicoxidation process, and the closeness of contact between the sidewall ofthe gas discharge hole 302a and the outer surface of the cylindricalexpanded part 244b of the insulating member 244 is deteriorated. Thus,the outer surface of the cylindrical, expanded part 244b of theinsulating member 244 is in close contact with the sidewall of the gasdischarge hole 302a. Consequently, the plasma is unable to infiltrateinto gaps between the sidewalls of the gas discharge holes 302a and theinsulating members 244.

In the conventional etching system of this type, a silicon electrode anda cooling plate are provided with gas discharge holes, and any memberscorresponding to the insulating members 244 are not used. Therefore, thegas discharge holes of the cooling plate are damaged by a plasmaproduced in a processing chamber 102 and the cooling plate must bechanged periodically. Since the insulating members 244 are fitted in thegas discharge holes 302a in the etching system in this embodiment, theetching of the sidewalls of the gas discharge holes 302a by the plasmaproduced in the processing chamber 102 can be prevented. Therefore, itis necessary to change only the insulating members 244 when necessaryand the cooling plate 302 does not need to be changed periodically.Since the lower end parts of the small holes 244c are tapered to formthe tapered lower end parts 244e, the sidewalls of the small holes 244care not etched quickly, and hence insulating member changing period atwhich the insulating members 244 are changed can be extended.

The insulating members 244 fitted in the gas discharge holes 302a may beof a shape other than that shown in FIGS. 6 and 7, provided that theinsulating members are able to cover the sidewalls of the gas dischargeholes 302a.

Although the preferred embodiments of the present invention have beendescribed with reference to the accompanying drawings, the presentinvention is not limited thereto in its practical application. It isobvious to those skilled in the art that many changes and variations arepossible without departing from the technical scope of the presentinvention.

Although the insulating members are fitted in the gas discharge holes inthe foregoing embodiment, the present invention is not limited thereto;each of the insulating member may be provided with an expansionextending over the rim of the opening of the gas discharge hole on theside of the processing chamber to cover edges formed in the open end ofthe gas discharge hole.

Although the insulating members are pressed into the gas discharge holesin the foregoing embodiment, an internal thread

1. A processing system comprising: a processing vessel defining anairtight processing chamber; an upper electrode disposed in an upperregion of the processing chamber; a lower electrode disposed below andopposite to the upper electrode in the processing chamber, and a radiofrequency power source connected at least to either the upper or thelower electrode; wherein the upper electrode includes a side facing intothe processing chamber towards the lower electrode, the upper electrodeside having a plurality of gas discharge holes to supply a predeterminedprocess gas therethrough into the processing chamber, resin insulatingmembers, each provided with a through hole permitting the process gas topass through, are fitted from the upper electrode side facing theprocessing chamber into the gas discharge holes, respectively, each ofthe gas discharge holes is provided with a shoulder, each of theinsulating members is provided with a step, and each of the insulatingmembers are positioned in the gas discharge hole with its step incontact with the shoulder of the gas discharge hole.
 2. The processingsystem according to claim 1, wherein the insulating members are fittedin the gas discharge holes of the upper electrode to project into theprocessing chamber.
 3. The processing system according to claim 1,wherein each of the insulating members is provided with a flange capableof covering the rim of an end of the gas discharge hole on the side ofthe processing chamber.
 4. The processing system according to claim 1,wherein at least part of the sidewall of each of the gas discharge holesbetween an open end thereof on the side of the processing chamber andthe shoulder thereof is finished by a plasma-proofing process, and apart of the sidewall of each gas discharge hole between the shoulder andthe open end opening into a gas supply passage is not finished by theplasma-proofing process.
 5. The processing system according to claim 4,wherein the insulating members are formed of a resin.
 6. The processingsystem according to claim 1, wherein each of the insulating members hasa length and the length of the insulating members is shorter than thatof the gas discharge holes.
 7. The processing system according to claim1, wherein at least part of the through hole of each insulating memberis substantially tapered so as to expand toward the processing chamber.8. A processing system comprising: a processing vessel defining anairtight processing chamber; an upper electrode disposed in an upperregion of the processing chamber; a lower electrode disposed below andopposite to the upper electrode in the processing chamber; and a radiofrequency power source connected at least to either the upper or thelower electrode; wherein the upper electrode has an upper electrodemember and a cooling plate disposed on the upper electrode member, theupper electrode member and the cooling plate are provided with aplurality of gas discharge holes through which a predetermined processgas is supplied into the processing chamber, resin insulating members,each provided with a through hole permitting the process gas to flowthrough, are fitted into the gas discharge holes so as to cover thesidewalls of the gas discharge holes, each of the discharge holes beingformed as a through hole passing through the upper electrode member andthe cooling plate, each of the gas discharge holes of the cooling plateis provided with a shoulder, each of the insulating members is providedwith a step, and the insulating members are positioned in the gasdischarge holes with the steps thereof resting on the shoulders of thecorresponding gas discharge holes, each of the insulating members isfitted into the cooling plate from an opposite side of the upperelectrode member.
 9. The processing system according to claim 8, whereinat least an end part of the through hole of each insulating member onthe side of the processing chamber is substantially tapered to expandtoward the processing chamber.
 10. An upper electrode unit for use in aprocessing vessel defining an airtight processing chamber, saidelectrode unit comprising: an upper electrode disposable in an upperregion of the processing chamber, said upper electrode provided with aplurality of gas discharge holes to supply a predetermined process gastherethrough into the processing chamber, each of the gas dischargeholes provided with a shoulder; and resin insulating members, eachprovided with a through hole permitting a process gas to pass through,fitted in the gas discharge holes, each of the insulating members arefitted with a step, wherein the insulating members are fitted in the gasdischarge holes so that the insulating members are positioned in placein the gas discharge holes with steps thereof resting on the shouldersof the corresponding gas discharge holes.
 11. The upper electrode unitaccording to claim 10, wherein the insulating members are fitted in thegas discharge holes of the upper electrode to project into theprocessing chamber.
 12. The upper electrode unit according to claim 10,wherein each of the insulating members is provided with a flange capableof covering a rim of an end of the gas discharge hole in the processingchamber.
 13. The upper electrode unit according to claim 10, wherein atleast part of the sidewall of each of the gas discharge holes between anopen end thereof in the processing chamber and the shoulder thereof isfinished by a plasma-proofing process, and a part of the sidewall ofeach gas discharge hole between the shoulder and the open end openinginto the gas supply passage is not finished by the plasma-proofingprocess.
 14. The upper electrode unit according to claim 10, whereineach of the insulating members has a length and the length of theinsulating members is shorter than that of the gas discharge holes. 15.The upper electrode unit according to claim 10, wherein at least part ofthe through hole of each insulating member is substantially tapered soas to expand toward the processing chamber.
 16. The upper electrode unitaccording to claim 10, wherein said resin insulating members are fittedin the gas discharge holes, respectively, from inside the processingchamber.
 17. An electrode unit for use in an airtight processing chamberhaving a susceptor therein, the electrode unit comprising: an electrodeprovided with a plurality of gas discharge holes to supply apredetermined process gas therethrough into the processing chamber, eachof the gas discharge holes provided with a shoulder, and resininsulating members, each provided with a step and with a through holepermitting the process gas to pass therethrough, each resin member beingpressed into one of the gas discharge holes so that the step of theresin member contacts with the shoulder of said one gas discharge holeand the resin member opposes the susceptor.
 18. An electrode unitaccording to claim 17, wherein the resin members project from the gasdischarge holes.
 19. An electrode unit according to claim 18, whereineach of the gas discharge holes has an end with a rim, each of the resinmembers has a flange, and the flanges of the resin members cover therims of the gas discharge holes.
 20. An electrode unit according toclaim 19, wherein each of the gas discharge holes has different interiordiameters.
 21. An electrode unit according to claim 20, wherein an openend of the hole permitting the process gas to pass therethroughsubstantially is tapered.
 22. An electrode unit according to claim 18,wherein each of the gas discharge holes has different interiordiameters.
 23. An electrode unit according to claim 22, wherein an openend of the hole permitting the process gas to pass therethroughsubstantially is tapered.